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Slightly later than officially planned, question of the week number 17, a weekly feature on security stack exchange is a rather unusual but very interesting choice. We’ve featured it by community votes – and because it’s an interesting study of “how to think about security”.

I did warn you! Well, never fear, it turns out our members know exactly how to do it! So without further ado:

Overview

In terms of radio communications security, most satellite communications systems are repeaters, accepting communication from the highest strength incoming signal at will. Most satellites then contain a command module to order the satellite to perform certain actions as necessary. Due to the highly custom nature of individual satellites, the commands that are accepted and the security for them is highly variable, so there’s a lot of potential for exploitation. As one of our answerers puts it:

When it comes to satellites, the word general does not apply.

Legal Concerns

As a result of the wide variety of frequencies and power requirements in use, chances are, attempting to send commands to a satellite are likely to violate local radio laws – as such, we do not recommend it (although we find the study of security very interesting, all the same).

Finding and talking to a satellite

Clearly, if you’re going to communicate with a satellite, you need equipment with sufficient power and range. You’ll need to be aware of the carrier frequency, the maximum satellite range, the data rate and satellite transmitter power. The location and altitude of satellites also matters – some are geostationary and as such are always in range, while others orbit and may only be in range for a specific period of time. Directional antennas with tracking motors will help an awful lot if the satellite changes position at all. Our answers provide even more detailed radio advice and links, so if you’re interested in your radio, do have a read!

Taking control of a satellite

There are several means by which you can take control of a satellite:

Direct comms: If you have identified your target satellite, the most obvious method would be to communicate directly with it, sending it the commands you desire. Depending on the satellite you target your options will vary. You’ll need to be aware of the protocol and options available to you.

MITM: One option for hijacking a satellite is to identify its command and control – the ground station – and intercept its communications. If you can afford to rent a small plane and can fly it over the site, possibly allowing you an advantage.

Doing it legally

It may be possible to purchase satellite time, depending on who you ask – and as such it may be possible to legitimately control a satellite, even if only for a brief period!

The expensive way

Many of the answers given focused on the radio communication protocols – however, Security.SE member and former moderator Graham Lee highlighted the physical security of satellites as a major concern – the only problem being the cost of getting into space. If you can, being able to nudge the satellite is enough to deny service by altering the antenna direction – you may be able to exploit it in other ways, whilst you’re up there. Of course, you don’t need to go up there yourself necessarily – a rocket will do the job adequately well and apparently doesn’t even need explosives!

Summary

Satellite security is an interesting area with many concerns that has perhaps been overlooked in our focus on the security of online stores and the like. Thankfully, people are looking at the security of communications systems that rely on satellites!

This QotW writeup relied on answers from Jeff Ferland, this.josh and Graham Lee primarily. Thanks to all our answerers on this particular question for providing their insights!

Can you improve on these answers? Feel free to visit the question and provide additional detail!